Question

Root hair absorbs water from the soil through
A. Turgor pressure
B. Ion exchange
C. Osmosis
D. DPD

Answer 1

Hint: Absorption of water is related to the process of transpiration.

Complete answer:
Root hairs are present in the zone of maturation of roots. They absorb water from the soil by the simple process of osmosis. It is a passive mechanism and no energy expenditure is required.

The mechanism of passive absorption of water is as follows:
- This process is seen in rapidly transpiring plants.
- Due to transpiration which is the loss of water vapor from the leaf surface, a pull is generated that acts along the length of xylem bundles. This pull acts as a force of water absorption and is known as transpirational pull.
- Due to this pull, the water present between soil particles (capillary water) is pulled through the root system of plants.
- It is a completely passive procedure and 96-98% of water reabsorption takes place by this procedure.
- Transpiration pull is also the fastest method of water absorption in plants.

Additional Information:
The water moves through the roots in the following two pathways:
- Symplastic Pathway: The movement of water occurs through the protoplasm of the plant cell. The cytoplasm and plasmodesmata connection are associated with symplastic transport.
- Apoplastic pathway: Transport of water occurs through the cell walls and intercellular spaces of the plant cell. It does not involve any living component like cytoplasm.
               

So, the correct answer is, “ Root hair absorbs water from the soil through osmosis.”

Note: Even though a maximum of the water absorption occurs by passive method, a small percentage of 2-4% of water absorption takes place by active method (osmotic active and non-osmotic active absorption)So, the correct answer is, "Herbivorous animals can digest cellulose because of bacteria present in their caecum help in the digestion of cellulose."